Categories: Synthesis of N-Heterocycles, Synthesis of S-Heterocycles >
Synthesis of isothiazoles
A base-promoted demethoxylative cycloaddition of alkynyl oxime ethers enables the synthesis of isoselenazoles and isothiazoles by using cheap and inactive Se powder or Na2S as selenium and sulfur sources. This one pot transformation offers excellent functional group tolerance.
Z.-Z. Zhang, R. Chen, X.-H. Zhang, X.-G. Zhang, J. Org. Chem., 2021, 86, 632-642.
A Rh-catalyzed transannulation of 1,2,3-thiadiazoles with alkyl, aryl, and heteroaryl nitriles provides a wide variety of isothiazoles via an α-thiavinyl Rh-carbenoid intermediate.
B. Seo, Y. G. Kim, P. H. Lee, Org. Lett., 2016, 18, 5050-5053.
Three-component reactions of enaminoesters, fluorodibromoiamides/ester, and sulfur provide thiazoles and isothiazoles via two C-F bond cleavages along with the formation of new C-S, C-N, and N-S bonds. Both methods offer high selectivity for the synthesis of thiazoles/isothiazoles, which have vital applications in drug discovery and development.
X. Ma, X. Yu, H. Huang, Y. Zhou, Q. Song, Org. Lett., 2020, 22, 5284-5288.
An operationally simple and user-friendly synthesis of 3,5-disubstituted/annulated isothiazoles from β-ketodithioesters/β-ketothioamides and NH4OAc via C=O/C=S bond functionalization under metal- and catalyst-free conditions. The carbon-economic [4 + 1] annulation relies on a sequential imine formation/cyclization/aerial oxidation cascade forming consecutive C-N and S-N bonds in one pot.
G. Shukla, A. Srivastava, M. S. Singh, Org. Lett., 2016, 18, 2451-2454.